Futago no Koi wa Minukenai

At Koiwaga Academy, there is a pair of famous twin sisters: Misono Hana and Misono Mana. They're identical twins, incredibly beautiful with flawless figures. Coming from a prestigious all-girls school background, they unexpectedly took a different path to Koiwaga Academy - and, with their novelty playing a part, they became the center of attention within a month.

The twins are always surrounded by a crowd, and the protagonist, Kishi Ryousuke, watches them from a distance - until one day, he suddenly notices them secretly posing as each other.

With no one else aware of the switch, Ryousuke, the only one who can tell the twins apart, quickly grows close to both of them. One day, the three of them cross a boundary, and their bond begins to deepen at an accelerating pace...

[Translated from the official website]